Cumulative air density depletion during high repetition rate filamentation of femtosecond laser pulses: Application to electric discharge triggering

We study the influence of laser repetition rate on generation low-density channels air left in path femtosecond filament. At high rates, we observe formation a permanent millimeter-wide channel that exceeds depth and width transient depletion due to single also show this cumulative effect decreases breakdown voltage between two electrodes can alter discharge. By comparing pure nitrogen, an accumulation O2− ions contributes reduction voltage.